It is known to provide an anterior cervical plate for attachment to the anterior of two or more cervical vertebrae for the purpose of immobilizing, stabilizing and/or aligning those vertebrae. The plates can be used for a variety of conditions including for example providing added strength and rigidity after fusion of adjacent vertebrae, securing vertebrae together where an intervening vertebrae has been removed and replaced, correcting spinal deformities, and correcting instability caused by trauma, tumors, advanced degenerative discs, infection or congenital or acquired deformities.
Cervical plates of the present type are generally elongated so as to span the distance between two, three, four or more vertebrae, as required in a given situation. The plates are generally curved transversely so as to fit the curvature of the vertebrae to which they are attached. Additionally, plates of this type are generally concave longitudinally thereof to match the curvature of the cervical spine. Cervical plates of this type are provided with holes for bone screws. Holes are drilled into the adjacent vertebrae by instruments which are known in the art, after which the cervical plate is attached by bone screws which pass through the holes in the cervical plate for securing the plate to the adjacent vertebrae.
Many cervical plates of the present type are known, each having various arrangements for securing the bone screws. Such arrangements are shown in prior U.S. Pat. Nos. 5,364,399; 5,549,612; 6,193,721; 6,224,602; 6,235,034; 6,383,186; and 6,454,771. Notwithstanding the development of the prior art to date, a need exists for improvements in arrangements for securing the bone screws in place after the bone screws have secured the cervical plate onto the adjacent vertebrae.